This disclosure relates generally to downhole radiation detectors and, more particularly, to gas-filled tube radiation detectors that collect a light signal using an internal optical fiber.
This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present techniques, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
Many different downhole tools are used to determine the properties of a geological formation surrounding a well. Some of these downhole tools detect radiation from the formation—either naturally occurring or emitted from a radiation source in the downhole tool—to ascertain the properties of the formation. The radiation detectors of these tools generally take one of two forms: a scintillation detector or a gas-filled tube radiation detector.
A scintillation detector detects radiation by converting the energy of the radiation into light. Specifically, scintillating crystals in the scintillation detector may generate light when incident radiation strikes the crystals. A photomultiplier tube (PMT) may amplify the light into an electrical signal that can be interpreted by electronic components. Although scintillation detectors are effective, they may be expensive to manufacturer.
Gas-filled tube radiation detectors, also commonly referred to as Geiger-Müller tubes, may present a lower-cost option. A gas-filled tube radiation detector may detect radiation using a tube filled with an ionizing gas in an electric field. When incident radiation enters the gas-filled tube, an ionization avalanche may occur that causes electrons to rapidly move toward an anode in the gas-filled tube. These electrons produce an electrical signal on the anode that can be detected by electronics. Although gas-filled tube radiation detectors may be less costly, these detectors may also be less sensitive than scintillation detectors. Moreover, both gas-filled tube radiation detectors and scintillation detectors may use electronics located near the detectors to collect the electrical signals. Electronics that are used near the detectors may be subject to harsh downhole environmental conditions.